B1aL5 Diet and Energy

Key Words

Balanced diet - intake of a variety of foods, all of which contain the correct amounts of nutrients for healthy growth and maintenance of the body.
Brown fat - fat cells that burn off excessive energy.
Carbohydrates - foods that have a lot of energy in the form of sugars and starches.
Energy - ability to do work.
Fats - large molecules made from fatty acids and glycerol.

Fibre - indigestible material that helps food to pass through the intestines.
Malnourished - a long term condition that results from an unbalanced diet, usually associated with not having enough food.
Metabolic rate - the rate at which food is turned into energy
Proteins - large molecules made up of long chains of fatty acids.
Respiration - conversion of glucose to carbon dioxide and water, giving off energy.

Grade E

A balanced diet has the right amounts of the following:

• carbohydrates - these are broken down quickly to give sugar for energy;

• proteins - needed for growth and repair;

• fats - needed for cell membranes, and long-term energy;

• vitamins - small molecules that are needed in small amounts to keep the body working properly;

• minerals - natural chemical compounds needed in very small amounts but needed to keep the body working properly;

• fibre - although not digested, fibre is needed to keep the food moving through the digestive system, and is removed when we go to the lavatory;

• water - essential for all life processes.

Energy containing foods are carbohydrates, fats, and proteins.

Too much of energy foods, and there is a risk of your becoming overweight, because the foods are turned into fat (flib-flob, spare tyres, etc).  Too little, and you become too thin to be healthy.

Inadequate intake of food, or an unbalanced diet leads to malnourishment.  And people do not need to be starving either to be malnourished.  A diet of junk food can lead to a range of health problems.  In more affluent areas, parents are so keen to avoid fats for their children that there is a phenomenon called muesli malnutrition.

Grade C

Younger people can eat a lot more than older people.  This is because their metabolic rate is higher.  The metabolic rate is the rate at which energy is burned up in the body.   Athletes such as the two below will burn up energy at a much quicker rate than the old man seen in the right, who was an athlete in his youth.

If there is a lot of muscle compared to fat, then the metabolic rate is a lot higher.  There is also brown fat that burns off any excess energy.  This found under the shoulder blades and the back of the neck.  When adrenalin is released in an angry situation, the brown fat turns on to get the body hot, ready for action.  This is the origin of the phrase hot under the collar.

The maximum energy requirements happen between about 13 and 25 for men, and 11 to 23 for women.  This coincides with the growth rate and the generally higher activity of younger people.  As one gets older, the muscle to fat ratio decreases.  The seventy year old man on the right needs to ear a lot less than the nineteen year olds on the left.

A pregnant woman needs to eat a lot more than she would normally, as she has two lives to maintain.

Babies have a lot of brown fat.

Grade A

The average basal metabolic rate is about 40 - 50 % of the total energy expenditure.  If you did nothing at all, you would still burn about 100 joules every second, 8.6 MJ every day (2000 kcal).

As long as you are are eating that, you will not gain weight.  However, it is not as simple as that.

• Genetic factors can make some people more prone to be overweight;

• The metabolic rate is affected by the activity you do.

A lot of money is made by those putting forward diet plans.  These tend to be passing fads, and the best diet plan was suggested by the MP Anne Widdicombe:

Eat less, exercise more.

And that exercise does not necessarily have to be strenuous.  In fact, sudden strenuous exercise can do a lot of damage, which is really not quite the point.